THURSDAY, Aug. 6, 2015 (HealthDay News) -- An online program that encourages people to wash their hands reduced the spread of cold and flu viruses within families, a new study says.

The program also led to fewer gastrointestinal illnesses, doctor appointments and antibiotic prescriptions, according to the findings published online Aug. 6 in The Lancet.

"A simple, cheap internet program to encourage hand washing can reduce the risk of infection by around 14 percent," study author Dr. Paul Little, a professor at the University of Southampton in the U.K., said in a journal news release.

"Because most of the population catches coughs, colds, sore throats and other respiratory infections, this could have an important impact on reducing the spread of these viruses in the general population, and also help reduce the pressure on [health] services during the winter months," he added.

The study included more than 20,000 people, aged 18 and older, in British households who were randomly assigned to use PRIMIT or to a control group that did not use the website.

Over 16 weeks of monitoring, 51 percent of people in the PRIMIT group had at least one respiratory infection, compared with 59 percent of those in the control group. That means those in the PRIMIT group had a 14 percent lower risk, the researchers said.

Those in the PRIMIT group had a 20 percent lower risk of catching a flu-like illness. They also had 10 percent to 15 percent fewer doctor visits and antibiotic prescriptions, the study found.

"Influenza is only one of the many infectious diseases that can affect populations. An even more important point to take from this study is therefore the promotion of hand washing as a generic routine to manage transfer of infections," Dr. Chris van Weel, a professor at Australian National University in Canberra, wrote in an accompanying commentary.